/*
       1. Case: Sample number
       2. Taste: Subjective taste test score, obtained by combining the
          scores of several tasters
       3. Acetic: Natural log of concentration of acetic acid
       4. H2S: Natural log of concentration of hydrogen sulfide
       5. Lactic: Concentration of lactic acid
*/

OPTIONS LS=80 NODATE;

DATA cheese;
   INPUT case y x1-x3;
   LABEL x1="acetic";
   LABEL x2="h2s";
   LABEL x3="lactic";
   CARDS;
     1       12.3    4.543   3.135   0.86
     2       20.9    5.159   5.043   1.53
     3       39      5.366   5.438   1.57
     4       47.9    5.759   7.496   1.81
     5       5.6     4.663   3.807   0.99
     6       25.9    5.697   7.601   1.09
     7       37.3    5.892   8.726   1.29
     8       21.9    6.078   7.966   1.78
     9       18.1    4.898   3.85    1.29
     10      21      5.242   4.174   1.58
     11      34.9    5.74    6.142   1.68
     12      57.2    6.446   7.908   1.9
     13      0.7     4.477   2.996   1.06
     14      25.9    5.236   4.942   1.3
     15      54.9    6.151   6.752   1.52
     16      40.9    6.365   9.588   1.74
     17      15.9    4.787   3.912   1.16
     18      6.4     5.412   4.7     1.49
     19      18      5.247   6.174   1.63
     20      38.9    5.438   9.064   1.99
     21      14      4.564   4.949   1.15
     22      15.2    5.298   5.22    1.33
     23      32      5.455   9.242   1.44
     24      56.7    5.855   10.199  2.01
     25      16.8    5.366   3.664   1.31
     26      11.6    6.043   3.219   1.46
     27      26.5    6.458   6.962   1.72
     28      0.7     5.328   3.912   1.25
     29      13.4    5.802   6.685   1.08
     30      5.5     6.176   4.787   1.25
;
RUN;


DATA tmp;
   x1=5; x2=5; x3=1; y=.;
run;

/* merge the big dataset called "cheese" with the little dataset "tmp" */
DATA cheese;  
   SET tmp cheese;
RUN;

PROC REG DATA=cheese;
   *COVB displays Sigmahat = Var(betahat);
   *P displays fitted values and residuals;
   MODEL y=x1 x2 x3/COVB P CLI CLM;   
   MODEL y=x2 x3/COVB P CLI CLM;   
   MODEL y=x1-x3/selection=cp;
RUN;

PROC INSIGHT;RUN;